Motor Driving Apparatus Slip Speed Control for Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor driving apparatuses face challenges in generating a large, desired torque when activated, due to errors in motor constants leading to excessive slip speed and magnetic flux reduction, which results in inadequate torque output.
Innovation Solution
A motor driving apparatus that calculates and controls current and frequency instructions directly based on the speed instruction value, adjusting the slip speed to a lower value at activation, rather than increasing magnetic flux, to prevent magnetic flux reduction and ensure desired torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magnetic flux instruction value is increased to obtain increased torque, then torque output is improved, but magnetic flux reduction occurs due to excessive slip speed caused by motor constant errors
Solution Approach 1:
The patent changes the control parameter from magnetic flux instruction value to slip speed instruction value. By directly controlling slip speed rather than magnetic flux, the system prevents magnetic flux reduction caused by excessive slip speed, while still achieving the desired torque output through optimized slip speed control during motor activation.
2Measurement precision
If conventional vector control is used to calculate current instructions, then control precision is maintained, but torque output is insufficient at activation due to excessive slip speed
Solution Approach 1:
The patent applies preliminary action by detecting motor activation state and preemptively adjusting the slip speed instruction value before normal vector control takes over. During activation, the slip speed instruction is set to a value lower than the calculated slip speed, preventing excessive slip speed and magnetic flux reduction before they occur, thereby ensuring adequate torque output from the start.
Solution Approach 2:
The patent introduces dynamic adjustment of control parameters based on motor operating state. The slip speed instruction value is dynamically changed depending on whether the motor is in activation state or normal operation state, allowing optimal torque control during activation while maintaining standard vector control performance during normal operation.
3Force
If slip speed is reduced to prevent magnetic flux reduction, then torque output is improved, but control complexity increases
Solution Approach 1:
The patent introduces an intermediary component (slip speed instruction value adjustment mechanism) that mediates between the motor activation state and the vector control system. This intermediary detects activation state and adjusts slip speed instructions accordingly, providing a simple yet effective solution that prevents magnetic flux reduction without significantly increasing overall control complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the generation of a desired torque by adjusting the ratio of frequency to current at activation, reducing magnetic flux reduction and maintaining torque output, even with errors in estimated speed, thereby overcoming the limitations of conventional systems.
Implementation Method 1
a PWM inverter 2, which is connected to a three-phase AC power source 1, performs PWM modulation for the three-phase instructions, and transmits the results, as the output voltage of the three-phase AC inverter, to an induction motor 3
Implementation Method 2
an induction motor 3
Data Source
AI summary
A motor driving apparatus includes: a current instruction calculator, for calculating a current instruction value based on a deviation between a speed instruction value and an estimated speed value; a current controller, for controlling an output current based on the current instruction value; a frequency instruction calculator, for calculating a frequency instruction value based on an output voltage instruction value or an output voltage detection value, wherein, when an induction motor is to be activated, the current instruction value and the frequency instruction value are calculated directly using the speed instruction value, and an output current and an output frequency are controlled in accordance with the current instruction value and the frequency instruction value.